To be fair, they are a business, so they have to find a way to make money. No different from Facebook or Instagram, where they provide a social platform and you disclose your information which they sell.
I find the reviews useful as long as you don't accept everything that's said at face value. The analysis of the site plan is particularly helpful in telling you what the views are and which stacks receive the west sun, though buyers should also double check the information on their own, ie, do their own verifications.